Impact:
The vulnerability could enable an attacker to access sensitive channels that have been restricted with the MCAUSER parameter. This would enable an attacker to gain full read and write access to all queues defined within the channel. Additionally, an attacker could perform remote fingerprinting of the software, alter the Queue Manager configuration and potentially execute Operating System commands through the creation of an appropriate trigger process. The latter would be dependent on the presence of an existing trigger monitor process running on the system. Additionally, on version 6 of the software an attacker could create a service to execute commands on the system.

Cause:
The vulnerability arises from an error in the state model responsible for permitting connections to a channel. A connection can be established to the Queue Manager if the "2035 Not Authorised" response is ignored and the connection attempt continues.

Interim Workaround:
The workarounds at the present time involve using additional security mechanisms such as Security Exits to protect all channels on a Queue Manager. Additionally, it is possible to use network filtering to restrict access to Websphere MQ services to trusted IP addresses only. It is also possible that correctly deploying and mandating the use of SSL client certificates will prevent an attacker from accessing the channels on the Queue Manager. IBM have released a fix pack, the link of which is provided below.